Data modification for predictive operations and devices incorporating same

ABSTRACT

Infusion systems, infusion devices, and related operating methods are provided. An exemplary method of operating an infusion device capable of delivering fluid to a user involves obtaining a sequence of measurements indicative of a condition of the user that is influenced by the fluid and modifying one or more unusable measurements in the sequence using one or more other usable measurements in the sequence to obtain a modified sequence of measurements. The method continues by determining a predicted value for the condition of the user at a time in the future based at least in part on the modified sequence of measurements and operating the infusion device in a manner that is influenced by the predicted value.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/104,960, filed Dec. 12, 2013.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally tomedical devices, and more particularly, embodiments of the subjectmatter relate to modifying measurement data sequences used incontrolling operations of a portable electronic device, such as a fluidinfusion device.

BACKGROUND

Infusion pump devices and systems are relatively well known in themedical arts, for use in delivering or dispensing an agent, such asinsulin or another prescribed medication, to a patient. A typicalinfusion pump includes a pump drive system which typically includes asmall motor and drive train components that convert rotational motormotion to a translational displacement of a plunger (or stopper) in areservoir that delivers medication from the reservoir to the body of auser via a fluid path created between the reservoir and the body of auser. Use of infusion pump therapy has been increasing, especially fordelivering insulin for diabetics.

Continuous insulin infusion provides greater control of a diabetic'scondition, and hence, control schemes are being developed that allowinsulin infusion pumps to monitor and regulate a user's blood glucoselevel in a substantially continuous and autonomous manner, for example,overnight while the user is sleeping. Regulating blood glucose level iscomplicated by variations in the response time for the type of insulinbeing used along with each user's individual insulin response.Predictive algorithms may be utilized to provide estimations of thefuture blood glucose levels as an aid in regulating the blood glucoselevel. Rather than continuously sampling and monitoring a user's bloodglucose level, which may compromise battery life, intermittentlyobtained blood glucose data samples may be utilized for determiningestimations of future blood glucose levels.

Problems arise, however, when one or more blood glucose data samplesintended for input to a predictive algorithm are corrupted, lost, orotherwise invalid, for example, due to noise, transmission errors, orthe like. For example, in the case of recursive prediction algorithms,the prediction algorithm may be reset to eliminate the so-called “bad”data from undesirably influencing the device operation. Such an approachalso incurs the lag time required for the prediction algorithm toachieve a desired level of reliability, and thus, would result in aninability to provide predictive control for periods of time.

BRIEF SUMMARY

An embodiment of a method of operating a device is provided. Anexemplary method involves obtaining a sequence of measurementsindicative of a condition of a user, modifying one or more unusablemeasurements in the sequence using one or more other measurements in thesequence to obtain a modified sequence of measurements, determining apredicted value for the condition based at least in part on the modifiedsequence of measurements, and operating the device in a manner that isinfluenced by the predicted value.

In one embodiment, a system is provided that includes a sensingarrangement and a control module coupled to the sensing arrangement. Thesensing arrangement obtains a sequence of measurements of a condition.The sensing arrangement and the control module are cooperativelyconfigured to modify a value for an unusable measurement in the sequenceof measurements, resulting in a modified sequence of measurements, anddetermine a predicted value for the condition based at least in part onthe modified sequence. The control module is configured to determine acommand for operating a device in a manner that is influenced by thepredicted value.

In another embodiment, an infusion system is provided. The infusionsystem includes a sensing arrangement and an infusion device. Thesensing arrangement obtains a sequence of measurements of a condition ina body of a user, modifies a value for an unusable measurement in thesequence to obtain a modified sequence of measurements, determines apredicted value for the condition based at least in part on the modifiedsequence, and transmits the predicted value and a current measurement ofthe condition. The infusion device receives the predicted value and thecurrent measurement. The infusion device includes a motor operable todeliver fluid to the body of the user and a control module coupled tothe motor to determine a command for operating the motor based at leastin part on the current measurement in a manner that is influenced by thepredicted value.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures, which may beillustrated for simplicity and clarity and are not necessarily drawn toscale.

FIG. 1 depicts an exemplary embodiment of an infusion system;

FIG. 2 depicts a plan view of an exemplary embodiment of a fluidinfusion device suitable for use in the infusion system of FIG. 1;

FIG. 3 is an exploded perspective view of the fluid infusion device ofFIG. 2;

FIG. 4 is a cross-sectional view of the fluid infusion device of FIGS.2-3 as viewed along line 4-4 in FIG. 3 when assembled with a reservoirinserted in the infusion device;

FIG. 5 is a block diagram of an exemplary control system suitable foruse in a fluid infusion device, such as the fluid infusion device ofFIG. 1;

FIG. 6 is a block diagram of an exemplary sensing arrangement suitablefor use in the control system of FIG. 5;

FIG. 7 is a block diagram of an exemplary pump control system suitablefor use in the control system of FIG. 5;

FIG. 8 is a flow diagram of an exemplary control process suitable foruse with the control system of FIG. 5;

FIG. 9 depicts a table of measurement sequences suitable for use withthe control process of FIG. 8;

FIG. 10 depicts a table of the measurement sequences of FIG. 9 aftermodifying unusable measurement samples and determining a predictedmeasurement value in accordance with one or more exemplary embodimentsof the control process of FIG. 8.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

While the subject matter described herein can be implemented in anyelectronic device that includes a motor, exemplary embodiments describedbelow are implemented in the form of medical devices, such as portableelectronic medical devices. Although many different applications arepossible, the following description focuses on a fluid infusion device(or infusion pump) as part of an infusion system deployment. For thesake of brevity, conventional techniques related to infusion systemoperation, insulin pump and/or infusion set operation, and otherfunctional aspects of the systems (and the individual operatingcomponents of the systems) may not be described in detail here. Examplesof infusion pumps may be of the type described in, but not limited to,U.S. Pat. Nos. 4,562,751; 4,685,903; 5,080,653; 5,505,709; 5,097,122;6,485,465; 6,554,798; 6,558,320; 6,558,351; 6,641,533; 6,659,980;6,752,787; 6,817,990; 6,932,584; and 7,621,893; each of which are hereinincorporated by reference.

Embodiments of the subject matter described herein generally relate tofluid infusion devices including a motor that is operable to linearlydisplace a plunger (or stopper) of a reservoir provided within the fluidinfusion device to deliver a dosage of fluid, such as insulin, to thebody of a user. As described in greater detail below, in exemplaryembodiments, the dosage commands that govern operation of the motor areinfluenced by not only a current (or most recent) measurement of acondition in the body of the user, but also a predicted value (oranticipated measurement) for that condition in the body of the user atsome point in the future. For example, an insulin dosage command may bedetermined based on a current blood glucose measurement for the user ina manner that is influenced by a predicted (or anticipated) bloodglucose level in the body of the user 30 minutes into the future. Inthis regard, the insulin dosage command determined based on the user'scurrent blood glucose level may be adjusted, modified, enabled and/ordisabled based on the predicted blood glucose level to increase thelikelihood (if not ensure) that the user's blood glucose level ismaintained within an acceptable range of values going forward. While thesubject matter is described herein in the context of a fluid infusiondevice for purposes of explanation, the subject matter is notnecessarily limited to such an implementation. For example, thepredicted value may be determined and/or utilized by a monitoring deviceto determine when and/or how the monitoring device should be operated toalert or otherwise notify a user (or one or more other individuals) of acondition in the body of the user, an operational status of an infusiondevice or another medical device associated with the user, and/or thelike.

As described in greater detail below in the context of FIGS. 5-10, inexemplary embodiments, a predicted blood glucose level is calculated orotherwise determined as a sum of the user's current blood glucose leveland a weighted estimate of the trend in the user's blood glucose levelthat is determined based on previously obtained blood glucose levels forthe user. In exemplary embodiments, the estimate of the trend iscalculated as a weighted sum of the differences between consecutivemeasurements that precede the current measurement. Thus, previouslyobtained blood glucose measurements for the user are stored or otherwisemaintained for use in calculating the estimate of the trend in adeterministic manner rather than a recursive manner. In exemplaryembodiments described herein, when one or more of the previouslyobtained blood glucose measurements are unusable for determining thepredicted value, one or more other blood glucose measurements are usedto obtain a modified measurement value that is substituted or otherwiseused in place of the unusable blood glucose measurement. In this manner,measurements that are deemed invalid, unacceptable, or otherwiseunreliable are excluded from use in determining the predicted value.Rather than disabling or otherwise resetting the prediction and/orwaiting until a full sequence of consecutive usable measurements isavailable, the modified measurement sequence is utilized to calculatethe predicted value and continue operation of the device in a mannerthat is influenced by the predicted value.

Turning now to FIG. 1, one exemplary embodiment of an infusion system100 includes, without limitation, a fluid infusion device (or infusionpump) 102, a sensing arrangement 104, a command control device (CCD)106, and a computer 108. The components of an infusion system 100 may berealized using different platforms, designs, and configurations, and theembodiment shown in FIG. 1 is not exhaustive or limiting. In practice,the infusion device 102 and the sensing arrangement 104 are secured atdesired locations on the body of a user (or patient), as illustrated inFIG. 1. In this regard, the locations at which the infusion device 102and the sensing arrangement 104 are secured to the body of the user inFIG. 1 are provided only as a representative, non-limiting, example. Theelements of the infusion system 100 may be similar to those described inU.S. patent application Ser. No. 13/049,803, the subject matter of whichis hereby incorporated by reference in its entirety.

In the illustrated embodiment of FIG. 1, the infusion device 102 isdesigned as a portable medical device suitable for infusing a fluid, aliquid, a gel, or other agent into the body of a user. In exemplaryembodiments, the infused fluid is insulin, although many other fluidsmay be administered through infusion such as, but not limited to, HIVdrugs, drugs to treat pulmonary hypertension, iron chelation drugs, painmedications, anti-cancer treatments, medications, vitamins, hormones, orthe like. In some embodiments, the fluid may include a nutritionalsupplement, a dye, a tracing medium, a saline medium, a hydrationmedium, or the like.

The sensing arrangement 104 generally represents the components of theinfusion system 100 configured to sense, detect, measure or otherwisequantify a condition of the user, and may include a sensor, a monitor,or the like, for providing data indicative of the condition that issensed, detected, measured or otherwise monitored by the sensingarrangement. In this regard, the sensing arrangement 104 may includeelectronics and enzymes reactive to a biological condition, such as ablood glucose level, or the like, of the user, and provide dataindicative of the blood glucose level to the infusion device 102, theCCD 106 and/or the computer 108. For example, the infusion device 102,the CCD 106 and/or the computer 108 may include a display for presentinginformation or data to the user based on the sensor data received fromthe sensing arrangement 104, such as, for example, a current glucoselevel of the user, a graph or chart of the user's glucose level versustime, device status indicators, alert messages, or the like. In otherembodiments, the infusion device 102, the CCD 106 and/or the computer108 may include electronics and software that are configured to analyzesensor data and operate the infusion device 102 to deliver fluid to thebody of the user based on the sensor data and/or preprogrammed deliveryroutines. Thus, in exemplary embodiments, one or more of the infusiondevice 102, the sensing arrangement 104, the CCD 106, and/or thecomputer 108 includes a transmitter, a receiver, and/or othertransceiver electronics that allow for communication with othercomponents of the infusion system 100, so that the sensing arrangement104 may transmit sensor data or monitor data to one or more of theinfusion device 102, the CCD 106 and/or the computer 108.

Still referring to FIG. 1, in various embodiments, the sensingarrangement 104 may be secured to the body of the user or embedded inthe body of the user at a location that is remote from the location atwhich the infusion device 102 is secured to the body of the user. Invarious other embodiments, the sensing arrangement 104 may beincorporated within the infusion device 102. In other embodiments, thesensing arrangement 104 may be separate and apart from the infusiondevice 102, and may be, for example, part of the CCD 106. In suchembodiments, the sensing arrangement 104 may be configured to receive abiological sample, analyte, or the like, to measure a condition of theuser.

As described above, in some embodiments, the CCD 106 and/or the computer108 may include electronics and other components configured to performprocessing, delivery routine storage, and to control the infusion device102 in a manner that is influenced by sensor data measured by and/orreceived from the sensing arrangement 104. By including controlfunctions in the CCD 106 and/or the computer 108, the infusion device102 may be made with more simplified electronics. However, in otherembodiments, the infusion device 102 may include all control functions,and may operate without the CCD 106 and/or the computer 108. In variousembodiments, the CCD 106 may be a portable electronic device. Inaddition, in various embodiments, the infusion device 102 and/or thesensing arrangement 104 may be configured to transmit data to the CCD106 and/or the computer 108 for display or processing of the data by theCCD 106 and/or the computer 108.

In some embodiments, the CCD 106 and/or the computer 108 may provideinformation to the user that facilitates the user's subsequent use ofthe infusion device 102. For example, the CCD 106 may provideinformation to the user to allow the user to determine the rate or doseof medication to be administered into the user's body. In otherembodiments, the CCD 106 may provide information to the infusion device102 to autonomously control the rate or dose of medication administeredinto the body of the user. In some embodiments, the sensing arrangement104 may be integrated into the CCD 106. Such embodiments may allow theuser to monitor a condition by providing, for example, a sample of hisor her blood to the sensing arrangement 104 to assess his or hercondition. In some embodiments, the sensing arrangement 104 and the CCD106 may be used for determining glucose levels in the blood and/or bodyfluids of the user without the use of, or necessity of, a wire or cableconnection between the infusion device 102 and the sensing arrangement104 and/or the CCD 106.

In some embodiments, the sensing arrangement 104 and/or the infusiondevice 102 are cooperatively configured to utilize a closed-loop systemfor delivering fluid to the user. Examples of sensing devices and/orinfusion pumps utilizing closed-loop systems may be found at, but arenot limited to, the following U.S. Pat. Nos. 6,088,608, 6,119,028,6,589,229, 6,740,072, 6,827,702, 7,323,142, and 7,402, 153, all of whichare incorporated herein by reference in their entirety. In suchembodiments, the sensing arrangement 104 is configured to sense ormeasure a condition of the user, such as, blood glucose level or thelike. The infusion device 102 is configured to deliver fluid in responseto the condition sensed by the sensing arrangement 104. In turn, thesensing arrangement 104 continues to sense or otherwise quantify acurrent condition of the user, thereby allowing the infusion device 102to deliver fluid continuously in response to the condition currently (ormost recently) sensed by the sensing arrangement 104 indefinitely. Insome embodiments, the sensing arrangement 104 and/or the infusion device102 may be configured to utilize the closed-loop system only for aportion of the day, for example only when the user is asleep or awake.

As described in greater detail below in the context of FIGS. 5-10, inexemplary embodiments, the sensing arrangement 104 and/or the infusiondevice 102 are cooperatively configured to determine one or morepredicted values for the condition in the body of the user at one ormore times in the future. Thereafter, the delivery of the fluid isinfluenced by the one or more predicted values indicative of theanticipated future condition of the user in addition to a recentlyobtained value indicative of the current condition of the user. Forexample, commands for operating the infusion device to deliver insulinmay be determined as a function of a currently sensed blood glucosevalue and one or more predicted blood glucose values in a manner thataccounts for the anticipated response time for the insulin and/or theuser using the preceding blood glucose measurement values and/or thepreceding dosage commands. To put it another way, the control of auser's blood glucose level to regulate the user's blood glucose levelusing the user's current blood glucose level may be influenced by one ormore predicted blood glucose levels for the user in the future.

FIGS. 2-4 depict one exemplary embodiment of a fluid infusion device 200(or alternatively, infusion pump) suitable for use in an infusionsystem, such as, for example, as infusion device 102 in the infusionsystem 100 of FIG. 1. The fluid infusion device 200 is a portablemedical device designed to be carried or worn by a patient (or user),and the fluid infusion device 200 may leverage a number of conventionalfeatures, components, elements, and characteristics of existing fluidinfusion devices, such as, for example, some of the features,components, elements, and/or characteristics described in U.S. Pat. Nos.6,485,465 and 7,621,893. It should be appreciated that FIGS. 2-4 depictsome aspects of the infusion device 200 in a simplified manner; inpractice, the infusion device 200 could include additional elements,features, or components that are not shown or described in detailherein.

As best illustrated in FIGS. 2-3, the illustrated embodiment of thefluid infusion device 200 includes a housing 202 adapted to receive afluid-containing reservoir 205. An opening 220 in the housing 202accommodates a fitting 223 (or cap) for the reservoir 205, with thefitting 223 being configured to mate or otherwise interface with tubing221 of an infusion set 225 that provides a fluid path to/from the bodyof the user. In this manner, fluid communication from the interior ofthe reservoir 205 to the user is established via the tubing 221. Theillustrated fluid infusion device 200 includes a human-machine interface(HMI) 230 (or user interface) that includes elements 232, 234 that canbe manipulated by the user to administer a bolus of fluid (e.g.,insulin), to change therapy settings, to change user preferences, toselect display features, and the like. The infusion device also includesa display element 226, such as a liquid crystal display (LCD) or anothersuitable display element, that can be used to present various types ofinformation or data to the user, such as, without limitation: thecurrent glucose level of the patient; the time; a graph or chart of thepatient's glucose level versus time; device status indicators; etc.

The housing 202 is formed from a substantially rigid material having ahollow interior 214 adapted to allow an electronics assembly 204, asliding member (or slide) 206, a drive system 208, a sensor assembly210, and a drive system capping member 212 to be disposed therein inaddition to the reservoir 205, with the contents of the housing 202being enclosed by a housing capping member 216. The opening 220, theslide 206, and the drive system 208 are coaxially aligned in an axialdirection (indicated by arrow 218), whereby the drive system 208facilitates linear displacement of the slide 206 in the axial direction218 to dispense fluid from the reservoir 205 (after the reservoir 205has been inserted into opening 220), with the sensor assembly 210 beingconfigured to measure axial forces (e.g., forces aligned with the axialdirection 218) exerted on the sensor assembly 210 responsive tooperating the drive system 208 to displace the slide 206. In variousembodiments, the sensor assembly 210 may be utilized to detect one ormore of the following: an occlusion in a fluid path that slows,prevents, or otherwise degrades fluid delivery from the reservoir 205 toa user's body; when the reservoir 205 is empty; when the slide 206 isproperly seated with the reservoir 205; when a fluid dose has beendelivered; when the infusion pump 200 is subjected to shock orvibration; when the infusion pump 200 requires maintenance.

Depending on the embodiment, the fluid-containing reservoir 205 may berealized as a syringe, a vial, a cartridge, a bag, or the like. Incertain embodiments, the infused fluid is insulin, although many otherfluids may be administered through infusion such as, but not limited to,HIV drugs, drugs to treat pulmonary hypertension, iron chelation drugs,pain medications, anti-cancer treatments, medications, vitamins,hormones, or the like. As best illustrated in FIGS. 3-4, the reservoir205 typically includes a reservoir barrel 219 that contains the fluidand is concentrically and/or coaxially aligned with the slide 206 (e.g.,in the axial direction 218) when the reservoir 205 is inserted into theinfusion pump 200. The end of the reservoir 205 proximate the opening220 may include or otherwise mate with the fitting 223, which securesthe reservoir 205 in the housing 202 and prevents displacement of thereservoir 205 in the axial direction 218 with respect to the housing 202after the reservoir 205 is inserted into the housing 202. As describedabove, the fitting 223 extends from (or through) the opening 220 of thehousing 202 and mates with tubing 221 to establish fluid communicationfrom the interior of the reservoir 205 (e.g., reservoir barrel 219) tothe user via the tubing 221 and infusion set 225. The opposing end ofthe reservoir 205 proximate the slide 206 includes a plunger 217 (orstopper) positioned to push fluid from inside the barrel 219 of thereservoir 205 along a fluid path through tubing 221 to a user. The slide206 is configured to mechanically couple or otherwise engage with theplunger 217, thereby becoming seated with the plunger 217 and/orreservoir 205. Fluid is forced from the reservoir 205 via tubing 221 asthe drive system 208 is operated to displace the slide 206 in the axialdirection 218 toward the opening 220 in the housing 202.

In the illustrated embodiment of FIGS. 3-4, the drive system 208includes a motor assembly 207 and a drive screw 209. The motor assembly207 includes a motor that is coupled to drive train components of thedrive system 208 that are configured to convert rotational motor motionto a translational displacement of the slide 206 in the axial direction218, and thereby engaging and displacing the plunger 217 of thereservoir 205 in the axial direction 218. In some embodiments, the motorassembly 207 may also be powered to translate the slide 206 in theopposing direction (e.g., the direction opposite direction 218) toretract and/or detach from the reservoir 205 to allow the reservoir 205to be replaced. In exemplary embodiments, the motor assembly 207includes a brushless DC (BLDC) motor having one or more permanentmagnets mounted, affixed, or otherwise disposed on its rotor. However,the subject matter described herein is not necessarily limited to usewith BLDC motors, and in alternative embodiments, the motor may berealized as a solenoid motor, an AC motor, a stepper motor, apiezoelectric caterpillar drive, a shape memory actuator drive, anelectrochemical gas cell, a thermally driven gas cell, a bimetallicactuator, or the like. The drive train components may comprise one ormore lead screws, cams, ratchets, jacks, pulleys, pawls, clamps, gears,nuts, slides, bearings, levers, beams, stoppers, plungers, sliders,brackets, guides, bearings, supports, bellows, caps, diaphragms, bags,heaters, or the like. In this regard, although the illustratedembodiment of the infusion pump utilizes a coaxially aligned drivetrain, the motor could be arranged in an offset or otherwise non-coaxialmanner, relative to the longitudinal axis of the reservoir 205.

As best shown in FIG. 4, the drive screw 209 mates with threads 402internal to the slide 206. When the motor assembly 207 is powered andoperated, the drive screw 209 rotates, and the slide 206 is forced totranslate in the axial direction 218. In an exemplary embodiment, theinfusion pump 200 includes a sleeve 211 to prevent the slide 206 fromrotating when the drive screw 209 of the drive system 208 rotates. Thus,rotation of the drive screw 209 causes the slide 206 to extend orretract relative to the drive motor assembly 207. When the fluidinfusion device is assembled and operational, the slide 206 contacts theplunger 217 to engage the reservoir 205 and control delivery of fluidfrom the infusion pump 200. In an exemplary embodiment, the shoulderportion 215 of the slide 206 contacts or otherwise engages the plunger217 to displace the plunger 217 in the axial direction 218. Inalternative embodiments, the slide 206 may include a threaded tip 213capable of being detachably engaged with internal threads 404 on theplunger 217 of the reservoir 205, as described in detail in U.S. Pat.Nos. 6,248,093 and 6,485,465, which are incorporated by referenceherein.

As illustrated in FIG. 3, the electronics assembly 204 includes controlelectronics 224 coupled to the display element 226, with the housing 202including a transparent window portion 228 that is aligned with thedisplay element 226 to allow the display 226 to be viewed by the userwhen the electronics assembly 204 is disposed within the interior 214 ofthe housing 202. The control electronics 224 generally represent thehardware, firmware, processing logic and/or software (or combinationsthereof) configured to control operation of the motor assembly 207and/or drive system 208, as described in greater detail below in thecontext of FIG. 5. Whether such functionality is implemented ashardware, firmware, a state machine, or software depends upon theparticular application and design constraints imposed on the embodiment.Those familiar with the concepts described here may implement suchfunctionality in a suitable manner for each particular application, butsuch implementation decisions should not be interpreted as beingrestrictive or limiting. In an exemplary embodiment, the controlelectronics 224 includes one or more programmable controllers that maybe programmed to control operation of the infusion pump 200.

The motor assembly 207 includes one or more electrical leads 236 adaptedto be electrically coupled to the electronics assembly 204 to establishcommunication between the control electronics 224 and the motor assembly207. In response to command signals from the control electronics 224that operate a motor driver (e.g., a power converter) to regulate theamount of power supplied to the motor from a power supply, the motoractuates the drive train components of the drive system 208 to displacethe slide 206 in the axial direction 218 to force fluid from thereservoir 205 along a fluid path (including tubing 221 and an infusionset), thereby administering doses of the fluid contained in thereservoir 205 into the user's body. Preferably, the power supply isrealized one or more batteries contained within the housing 202.Alternatively, the power supply may be a solar panel, capacitor, AC orDC power supplied through a power cord, or the like. In someembodiments, the control electronics 224 may operate the motor of themotor assembly 207 and/or drive system 208 in a stepwise manner,typically on an intermittent basis; to administer discrete precise dosesof the fluid to the user according to programmed delivery profiles.

Referring to FIGS. 2-4, as described above, the user interface 230includes HMI elements, such as buttons 232 and a directional pad 234,that are formed on a graphic keypad overlay 231 that overlies a keypadassembly 233, which includes features corresponding to the buttons 232,directional pad 234 or other user interface items indicated by thegraphic keypad overlay 231. When assembled, the keypad assembly 233 iscoupled to the control electronics 224, thereby allowing the HMIelements 232, 234 to be manipulated by the user to interact with thecontrol electronics 224 and control operation of the infusion pump 200,for example, to administer a bolus of insulin, to change therapysettings, to change user preferences, to select display features, to setor disable alarms and reminders, and the like. In this regard, thecontrol electronics 224 maintains and/or provides information to thedisplay 226 regarding program parameters, delivery profiles, pumpoperation, alarms, warnings, statuses, or the like, which may beadjusted using the HMI elements 232, 234. In various embodiments, theHMI elements 232, 234 may be realized as physical objects (e.g.,buttons, knobs, joysticks, and the like) or virtual objects (e.g., usingtouch-sensing and/or proximity-sensing technologies). For example, insome embodiments, the display 226 may be realized as a touch screen ortouch-sensitive display, and in such embodiments, the features and/orfunctionality of the HMI elements 232, 234 may be integrated into thedisplay 226 and the HMI 230 may not be present. In some embodiments, theelectronics assembly 204 may also include alert generating elementscoupled to the control electronics 224 and suitably configured togenerate one or more types of feedback, such as, without limitation:audible feedback; visual feedback; haptic (physical) feedback; or thelike.

Referring to FIGS. 3-4, in accordance with one or more embodiments, thesensor assembly 210 includes a back plate structure 250 and a loadingelement 260. The loading element 260 is disposed between the cappingmember 212 and a beam structure 270 that includes one or more beamshaving sensing elements disposed thereon that are influenced bycompressive force applied to the sensor assembly 210 that deflects theone or more beams, as described in greater detail in U.S. patentapplication Ser. No. 12/908,807, which is incorporated by referenceherein. In exemplary embodiments, the back plate structure 250 isaffixed, adhered, mounted, or otherwise mechanically coupled to thebottom surface 238 of the drive system 208 such that the back platestructure 250 resides between the bottom surface 238 of the drive system208 and the housing cap 216. The drive system capping member 212 iscontoured to accommodate and conform to the bottom of the sensorassembly 210 and the drive system 208. The drive system capping member212 may be affixed to the interior of the housing 202 to preventdisplacement of the sensor assembly 210 in the direction opposite thedirection of force provided by the drive system 208 (e.g., the directionopposite direction 218). Thus, the sensor assembly 210 is positionedbetween the motor assembly 207 and secured by the capping member 212,which prevents displacement of the sensor assembly 210 in a downwarddirection opposite the direction of arrow 218, such that the sensorassembly 210 is subjected to a reactionary compressive force when thedrive system 208 and/or motor assembly 207 is operated to displace theslide 206 in the axial direction 218 in opposition to the fluid pressurein the reservoir 205. Under normal operating conditions, the compressiveforce applied to the sensor assembly 210 is correlated with the fluidpressure in the reservoir 205. As shown, electrical leads 240 areadapted to electrically couple the sensing elements of the sensorassembly 210 to the electronics assembly 204 to establish communicationto the control electronics 224, wherein the control electronics 224 areconfigured to measure, receive, or otherwise obtain electrical signalsfrom the sensing elements of the sensor assembly 210 that are indicativeof the force applied by the drive system 208 in the axial direction 218.

FIG. 5 depicts an exemplary embodiment of a control system 500 suitablefor use with an infusion device 502, such as the infusion device 102 inFIG. 1 or the infusion device 200 of FIG. 2. The control system 500 isconfigured to control or otherwise regulate a condition in the body 501of a user to a desired (or target) value or otherwise maintain thecondition within a range of acceptable values. In one or more exemplaryembodiments, the condition being regulated is sensed, detected, measuredor otherwise quantified by a sensing arrangement 504 (e.g., sensingarrangement 104) communicatively coupled to the infusion device 502.However, it should be noted that in alternative embodiments, thecondition being regulated by the control system 500 may be correlativeto the measured values obtained by the sensing arrangement 504. Forexample, the condition being regulated could be a blood glucose level oranother condition that is influenced by physical activity of the user,and the sensing arrangement 504 may be realized as a heart rate monitor,a gyroscope, an accelerometer, or another suitable physiological sensorthat provides measured values indicative of the level of physicalactivity being exhibited by the user.

It should be appreciated that FIG. 5 is a simplified representation ofthe infusion device 502 for purposes of explanation and is not intendedto limit the subject matter described herein in any way. In this regard,more complex control schemes may be implemented by the control system500 with multiple sensing arrangements 504 being utilized in conjunctionwith one another. For example, a blood glucose sensing device may beused with a heart rate monitor to implement a control scheme thatregulates a user's blood glucose level based on the measured bloodglucose level in a manner that accounts for the user's level of physicalactivity. That said, for clarity and ease of explanation, the subjectmatter may be described herein in the context of the control system 500having an individual sensing arrangement 504 that senses, detects,measures or otherwise quantifies the condition being regulated.

In the illustrated embodiment, the infusion device 502 includes a motorcontrol module 512 coupled to a motor 507 (e.g., motor assembly 207)that is operable to displace a plunger 517 (e.g., plunger 217) in areservoir (e.g., reservoir 205) and provide a desired amount of fluid tothe body 501 of a user. In this regard, displacement of the plunger 517results in the delivery of a fluid that is capable of influencing thecondition in the body 501 of the user to the body 501 of the user via afluid delivery path (e.g., via tubing 221 of an infusion set 225). Amotor driver module 514 is coupled between an energy source 503 and themotor 507. The motor control module 512 is coupled to the motor drivermodule 514, and the motor control module 512 generates or otherwiseprovides command signals that operate the motor driver module 514 toprovide current (or power) from the energy source 503 to the motor 507to displace the plunger 517 in response to receiving, from a pumpcontrol system 520, a dosage command indicative of the desired amount offluid to be delivered. In this regard, the pump control system 520generally represents the electronics and other components that controloperation of the fluid infusion device 502 according to a desiredinfusion delivery program in a manner that is influenced by sensor datapertaining to a condition of a user (e.g., the user's current glucoselevel) received from the sensing arrangement 504 and/or in a manner thatis dictated by the user. To support closed-loop control, the pumpcontrol system 520 receives or otherwise obtains a desired value (e.g.,a target or command blood glucose value) for the condition in the body501 of the user. For example, the infusion device 502 may store orotherwise maintain the target value in a data storage element accessibleto the pump control system 520. Alternatively, the target value may bereceived from an external component (e.g., CCD 106 and/or computer 108).

In exemplary embodiments, the energy source 503 is realized as a batteryhoused within the infusion device 502 (e.g., within housing 202) thatprovides direct current (DC) power. In this regard, the motor drivermodule 514 generally represents the combination of circuitry, hardwareand/or other electrical components configured to convert or otherwisetransfer DC power provided by the energy source 503 into alternatingelectrical signals applied to respective phases of the stator windingsof the motor 507 that result in current flowing through the statorwindings that generates a stator magnetic field and causes the rotor ofthe motor 507 to rotate. The motor control module 512 is configured toreceive or otherwise obtain a commanded dosage from the pump controlsystem 520, convert the commanded dosage to a commanded translationaldisplacement of the plunger 517, and command, signal, or otherwiseoperate the motor driver module 514 to cause the rotor of the motor 507to rotate by an amount that produces the commanded translationaldisplacement of the plunger 517. For example, the motor control module512 may determine an amount of rotation of the rotor required to producetranslational displacement of the plunger 517 that achieves thecommanded dosage received from the pump control system 520. Based on thecurrent rotational position (or orientation) of the rotor with respectto the stator that is indicated by the output of the rotor sensingarrangement 516, the motor control module 512 determines the appropriatesequence of alternating electrical signals to be applied to therespective phases of the stator windings that should rotate the rotor bythe determined amount of rotation from its current position (ororientation). In embodiments where the motor 507 is realized as a BLDCmotor, the alternating electrical signals commutate the respectivephases of the stator windings at the appropriate orientation of therotor magnetic poles with respect to the stator and in the appropriateorder to provide a rotating stator magnetic field that rotates the rotorin the desired direction. Thereafter, the motor control module 512operates the motor driver module 514 to apply the determined alternatingelectrical signals (e.g., the command signals) to the stator windings ofthe motor 507 to achieve the desired delivery of fluid to the user.

When the motor control module 512 is operating the motor driver module514, current flows from the energy source 503 through the statorwindings of the motor 507 to produce a stator magnetic field thatinteracts with the rotor magnetic field. In some embodiments, after themotor control module 512 operates the motor driver module 514 and/ormotor 507 to achieve the commanded dosage, the motor control module 512ceases operating the motor driver module 514 and/or motor 507 until asubsequent dosage command is received. In this regard, the motor drivermodule 514 and the motor 507 enter an idle state during which the motordriver module 514 effectively disconnects or isolates the statorwindings of the motor 507 from the energy source 503. In other words,current does not flow from the energy source 503 through the statorwindings of the motor 507 when the motor 507 is idle, and thus, themotor 507 does not consume power from the energy source 503 in the idlestate, thereby improving efficiency.

Depending on the embodiment, the motor control module 512 may beimplemented or realized with a general purpose processor, amicroprocessor, a controller, a microcontroller, a state machine, acontent addressable memory, an application specific integrated circuit,a field programmable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof, designed to perform the functions described herein.Furthermore, the steps of a method or algorithm described in connectionwith the embodiments disclosed herein may be embodied directly inhardware, in firmware, in a software module executed by the motorcontrol module 512, or in any practical combination thereof. Inexemplary embodiments, the motor control module 512 includes orotherwise accesses a data storage element or memory, including any sortof random access memory (RAM), read only memory (ROM), flash memory,registers, hard disks, removable disks, magnetic or optical massstorage, or any other short or long term storage media or othernon-transitory computer-readable medium, which is capable of storingprogramming instructions for execution by the motor control module 512.The computer-executable programming instructions, when read and executedby the motor control module 512, cause the motor control module 512 toperform the tasks, operations, functions, and processes describedherein.

As described in greater detail below in the context of FIGS. 6-10, inexemplary embodiments, the pump control system 520 generates orotherwise determines the dosage commands for operating the motor 507 todisplace the plunger 517 based at least in part on a measurement valueindicative of the current condition in the body 501 of the user in amanner that is influenced by a predicted value for the condition. Inthis regard, the predicted value is calculated based at least in part onthe most recent (or current) measurement value and represents anestimate of the anticipated condition in the body 501 of the user at aparticular point of time in the future. In exemplary embodiments, thepump control system 520 may adjust or override the dosage command forregulating the condition of the user based on the predicted value. Forexample, the pump control system 520 may suspend fluid delivery (e.g.,by disabling the dosage command or setting the dosage command to zero)when the predicted value falls below a suspend delivery threshold valueand resume fluid delivery (e.g., by enabling the dosage command ordetermining a nonzero dosage command using the current measurementvalue) when the predicted value exceeds a resume delivery thresholdvalue. In exemplary embodiments, the resume delivery threshold value isdifferent from the suspend delivery threshold value. For example, theresume delivery threshold value may be equal to the suspend deliveryvalue plus some offset value (which may be a percentage of the suspenddelivery value). In other embodiments, the resume delivery thresholdvalue may be equal to the suspend delivery threshold value.

In accordance with one or more embodiments, based on the predictedvalue, the pump control system 520 may adjust the dosage command forregulating the condition of the user based on the observed condition ofthe user and the trends in the user's condition. For example, if apredicted blood glucose level indicates that the user's blood glucoselevel is expected to fall below a lower threshold value, the pumpcontrol system 520 may reduce the dosage command (e.g., to zero or someother relatively smaller amount) to ensure the blood glucose level ismaintained above the lower threshold value, even though the currentblood glucose measurement value indicates the blood glucose level issufficiently above the lower threshold value. Conversely, if thepredicted blood glucose level indicates that the user's blood glucoselevel is expected to exceed an upper threshold value, the pump controlsystem 520 may increase the dosage command to ensure the blood glucoselevel is maintained below the upper threshold value, even though thecurrent blood glucose measurement value indicates the blood glucoselevel is sufficiently below the upper threshold value. For example, if atarget blood glucose level is between a resume delivery threshold valueand a suspend delivery threshold value, the pump control system 520 maydecrease and/or increase the dosage command to attempt to maintain theblood glucose level between the resume delivery threshold value and thesuspend delivery threshold value, and thereby improve the likelihood ofthe blood glucose level being maintained at or near the target value.

In some embodiments, the pump control system 520 may generate orotherwise provide an alert based on the predicted value. For example,the pump control system 520 may generate or otherwise provide anauditory and/or visual notification to the user associated with theinfusion device 502 that fluid delivery can or should be suspended whenthe predicted value falls below a threshold value and/or that fluiddelivery can or should be resumed.

In exemplary embodiments, the predicted value is calculated by addingthe current measurement value to a weighted sum determined using thepreceding measurement values. In this regard, a sequence of the mostrecently obtained measurement values for the condition in the body 501of the user is stored or otherwise maintained. For example, in oneembodiment, the predicted value is calculated using a truncated Taylorseries expansion or a recursive prediction algorithm, such as aHolt-Winters exponential smoothing function. In some embodiments, thesensing arrangement 504 includes a data storage element (or memory) forstoring the sensor data sequence comprised of the current measurementvalue and a number of preceding measurement values, as described ingreater detail below in the context of FIG. 6. Additionally, in suchembodiments, the sensing arrangement 504 may calculate or otherwisedetermine the predicted value for the condition in the body 501 of theuser based on the stored sensor measurement data sequence and transmitor otherwise provide the predicted value to the pump control system 520along with the current measurement value. Alternatively, the sensingarrangement 504 may transmit or otherwise provide the sensor measurementdata sequence to the pump control system 520, which, in turn, calculatesthe predicted value using the sensor data sequence received from thesensing arrangement 504. In yet other embodiments, the pump controlsystem 520 may maintain a sensor measurement data sequence comprised ofthe current measurement value and a number of preceding measurementvalues received from the sensing arrangement 504 (e.g., by queuing orbuffering the most recently received current measurement values), andbased on the stored sensor measurement data sequence and the currentmeasurement value received from the sensing arrangement 504, the pumpcontrol system 520 determines the predicted value for the condition inthe body 501 of the user, as described in the context of FIG. 7.

As described in the context of FIGS. 8-10, in exemplary embodiments,either the sensing arrangement 504 or the pump control system 520analyzes or otherwise monitors the sensor measurement data sequenceand/or the current measurement value to detect or otherwise identifywhen one or more measurement values in the sequence are invalid,unreliable, unacceptable, or otherwise unusable. In this regard, ameasurement value is unusable when one or more characteristics of themeasurement value is indicative of the measurement value beingcorrupted, unreliable, or otherwise unacceptable for purposes ofdetermining a predicted value based thereon. In response to detecting anunusable measurement value in a sensor measurement data sequence, thesensing arrangement 504 and/or the pump control system 520 modifies thesensor measurement data sequence to ameliorate the invalid measurementvalue, for example, by interpolating that value in the measurementsequence using acceptable measurement values that precede and succeedthe unusable measurement or replacing the unusable measurement value inthe sequence with a value of a succeeding measurement value in thesequence. In this manner, by virtue of modifying the sensor measurementdata sequence and calculating the predicted value in a deterministicmanner, a relatively reliable predicted value may be determined andutilized without having to reset the prediction calculation (e.g.,deleting or discarding the measurement sequence) and/or incur theadditional lag time associated with resetting the prediction calculationand/or waiting for a complete sequence of usable values to be obtained(e.g., the time required for the data sequence to be filled with theusable measurement values).

Again, it should be understood that FIG. 5 depicts a simplifiedrepresentation of the infusion device 502 for purposes of explanationand is not intended to limit the subject matter described herein in anyway. In this regard, depending on the embodiment, some features and/orfunctionality of the sensing arrangement 504 may implemented by orotherwise integrated into the pump control system 520, or vice versa.Similarly, in practice, the features and/or functionality of the motorcontrol module 512 may implemented by or otherwise integrated into thepump control system 520, or vice versa. Furthermore, the features and/orfunctionality of the pump control system 520 may be implemented bycontrol electronics 224 located in the fluid infusion device 200, 400,while in alternative embodiments, the pump control system 520 may beimplemented by a remote computing device that is physically distinctand/or separate from the infusion device 502, such as, for example, thedevice 106 or the device 108. Additionally, although FIG. 5 depicts thesensing arrangement 504 as being physically separate and distinct fromthe infusion device 502, in alternative embodiments, the sensingarrangement 504 may be integrated into or otherwise implemented by theinfusion device 502 (e.g., by providing the sensing arrangement 504within the housing 202).

FIG. 6 depicts an exemplary embodiment of a sensing arrangement 600suitable for use as the sensing arrangement 504 in FIG. 5 in accordancewith one or more embodiments. The illustrated sensing arrangement 600includes, without limitation, a control module 602, a sensing element604, a communications interface 606, and a data storage element (ormemory) 608. The control module 602 is coupled to the sensing element604, the communications interface 606, and the memory 608, and thecontrol module 602 is suitably configured to support the operations,tasks, and/or processes described herein.

The sensing element 604 generally represents the component of thesensing arrangement 600 that are configured to generate, produce, orotherwise output one or more electrical signals indicative of acharacteristic that is sensed, measured, or otherwise quantified by thesensing arrangement. In this regard, a characteristic of the outputelectrical signal provided by the sensing element 604 corresponds or isotherwise correlative to the characteristic that the sensing element 604senses, detects, measures, or otherwise quantifies. For example,referring to FIG. 5, the sensing element 604 may be realized as aglucose sensing element that generates an electrical signal, wherein acurrent (or voltage) associated with the electrical signal iscorrelative to the blood glucose level that is sensed or otherwisemeasured in the body 501 of the user.

Still referring to FIG. 6, the control module 602 generally representsthe hardware, circuitry, logic, firmware and/or other component of thesensing arrangement 600 that is coupled to the sensing element 604, andthe control module 602 is configured to receive the measurement datafrom the sensing element 604 and perform various additional tasks,operations, functions and/or operations described herein. For example,in one or more embodiments, the control module 602 implements orotherwise executes a data management application 610 that processes themeasurement data received from the sensing element 604 to detect orotherwise identify whether measurement data value received from thesensing element 604 is valid or otherwise acceptable, and when ameasurement data value is unacceptable, the data management application610 substitutes a modified measurement data value for the unacceptablemeasurement data value in a data sequence of the most recent measurementdata values. Additionally, in one or more embodiments, the controlmodule 602 also implements or otherwise executes a data predictionapplication 612 that calculates or otherwise determines one or morepredicted values for the characteristic sensed by the sensing element604 based on the sequence of the most recent measurement data valuesreceived from the data management application 610. In this regard, apredicted value for the sensed characteristic at a time in the futuremay be influenced by or otherwise based at least in part on the modifiedmeasurement data value substituted by the data management application610 in lieu of the unacceptable measurement data value received from thesensing element 604, as described in greater detail below.

Depending on the embodiment, the control module 602 may be implementedor realized with a general purpose processor, a microprocessor, acontroller, a microcontroller, a state machine, a content addressablememory, an application specific integrated circuit, a field programmablegate array, any suitable programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof, designed to perform the functions described herein. In thisregard, the steps of a method or algorithm described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in firmware, in a software module executed by the control module 602, orin any practical combination thereof. In some embodiments, the controlmodule 602 includes an analog-to-digital converter (ADC) or anothersimilar sampling arrangement that converts the output data signalreceived from the sensing element 604 into corresponding digitalmeasurement data value. For example, the control module 602 may convertan output electrical signal received from the sensing element 604 intocorresponding digital measurement value (e.g., an uncalibrated glucosesensor electrical current value).

In exemplary embodiments, the control module 602 includes or otherwiseaccesses the data storage element or memory 608. The memory 608 may berealized using any sort of RAM, ROM, flash memory, registers, harddisks, removable disks, magnetic or optical mass storage, short or longterm storage media, or any other non-transitory computer-readable mediumcapable of storing programming instructions for execution by the controlmodule 602. The computer-executable programming instructions, when readand executed by the control module 602, cause the control module 602 toimplement or otherwise generate the applications 610, 612 and performthe tasks, operations, functions, and processes described in greaterdetail below.

The communications interface 606 generally represents the hardware,circuitry, logic, firmware and/or other components of the sensingarrangement 600 that are coupled to the control module 602 andconfigured to support communications to/from the sensing arrangement600. The communications interface 606 may include or otherwise becoupled to one or more transceiver modules capable of supportingwireless communications between the sensing arrangement 600 and anotherelectronic device (e.g., an infusion device 102, 502 or anotherelectronic device 106, 108 in an infusion system 100). Alternatively,the communications interface 606 may be realized as a port that isadapted to receive or otherwise be coupled to a wireless adapter thatincludes one or more transceiver modules and/or other components thatsupport the operations of the sensing arrangement 600 described herein.In other embodiments, the communications interface 606 may be configuredto support wired communications to/from the sensing arrangement 600.

It should be understood that FIG. 6 is a simplified representation of asensing arrangement 600 for purposes of explanation and is not intendedto limit the subject matter described herein in any way. In this regard,although FIG. 6 depicts the various elements residing within the sensingarrangement 600, one or more elements of the sensing arrangement 600 maybe distinct or otherwise separate from the other elements of the sensingarrangement 600. For example, the sensing element 604 may be separateand/or physically distinct from the control module 602 and/or thecommunications interface 606. Furthermore, although FIG. 6 depicts thedata management application 610 and the data prediction application 612as being implemented by the sensing arrangement 600, in alternativeembodiments, features and/or functionality of the data managementapplication 610 and/or the data prediction application 612 may beimplemented by or otherwise reside on the infusion device 102, 502 oranother device 106, 108 within an infusion system 100. For example, asdescribed in greater detail below, in some embodiments, the datamanagement application 610 implemented by the sensing arrangement 600may merely detect or otherwise identify unacceptable measurement datavalues and provide a corresponding notification of the unacceptablemeasurement data value to the infusion device 102, 502, which, in turn,substitutes a modified measurement data value for the unacceptablemeasurement data value and determines one or more predicted values forthe sensed characteristic based thereon.

FIG. 7 depicts an exemplary embodiment of a pump control system 700suitable for use as the pump control system 520 in FIG. 5 in accordancewith one or more embodiments. The illustrated pump control system 700includes, without limitation, a pump control module 702, acommunications interface 704, and a data storage element (or memory)706. The pump control module 702 is coupled to the communicationsinterface 704 and the memory 706, and the pump control module 702 issuitably configured to support the operations, tasks, and/or processesdescribed herein.

Referring to FIG. 7 and with reference to FIG. 5, the communicationsinterface 704 generally represents the hardware, circuitry, logic,firmware and/or other components of the pump control system 700 that arecoupled to the pump control module 702 and configured to supportcommunications between the pump control system 700 and the sensingarrangement 504. In this regard, the communications interface 704 mayinclude or otherwise be coupled to one or more transceiver modulescapable of supporting wireless communications between the pump controlsystem 520, 700 and the sensing arrangement 504 or another electronicdevice 106, 108 in an infusion system 100. In other embodiments, thecommunications interface 704 may be configured to support wiredcommunications to/from the sensing arrangement 504.

The pump control module 702 generally represents the hardware,circuitry, logic, firmware and/or other component of the pump controlsystem 700 that is coupled to the communications interface 704 andconfigured to determine dosage commands for operating the motor 507 todeliver fluid to the body 501 based on data received from the sensingarrangement 504 and perform various additional tasks, operations,functions and/or operations described herein. For example, in exemplaryembodiments, pump control module 702 implements or otherwise executes acommand generation application 714 that calculates or otherwisedetermines a dosage command for operating the motor 507 of the infusiondevice 502 based at least in part on a current measurement value for acondition in the body 501 of the user, a predicted measurement value forthat condition in the body 501 of the user, and one or more reference(or target) values for that condition in the body 501 of the user. Forexample, the command generation application 714 may determine a dosagecommand for operating the motor 507 to deliver insulin to the body 501of the user based at least in part on a current blood glucosemeasurement value, a predicted blood glucose measurement value at a timein the future (e.g., in 30 minutes from the current time), and areference glucose value. For example, the reference value may be equalto the threshold blood glucose value at which insulin delivery should besuspended, wherein the command generation application 714 sets thedosage command to zero to suspend operation of the motor 507 (andthereby, suspend delivery) when the current blood glucose measurementvalue is less than or equal to the threshold blood glucose value.Conversely, when the current blood glucose measurement value is greaterthan a threshold blood glucose value (e.g., the resume deliverythreshold), the command generation application 714 may determine anonzero dosage command for operating the motor 507 to deliver insulin tothe body 501 of the user based at least in part on the current bloodglucose measurement value. In the case of closed-loop control, thedosage command determined by the command generation application 714 maybe configured to regulate the user's blood glucose level to a targetblood glucose value.

Referring to FIG. 7 with reference to FIGS. 5-6, in some embodiments,the pump control module 702 may also implement or otherwise execute adata prediction application 712 and/or a data management application 710in lieu of and/or in addition to the applications 610, 612 beingimplemented by the sensing arrangement 504, 600. In this regard, in someembodiments, the sensing arrangement 504, 600 may merely transmit thecurrent measurement value and/or a sequence of recent measurementvalues, either with or without indications of whether those measurementvalues are valid and/or acceptable. In such embodiments, the datamanagement application 710 on the pump control module 702 may processthe measurement data received from the sensing arrangement 504, 600 todetect or otherwise identify whether any of the measurement data valuesreceived from the sensing arrangement 504, 600 are invalid or otherwiseunacceptable. In this regard, the data management application 710 mayalso detect or otherwise measurement data values that were dropped,lost, or otherwise failed to be received by the communications interface704. In a similar manner as described above, the data managementapplication 710 substitutes a modified measurement data value for anunacceptable measurement data value to provide a modified data sequencefor the most recent measurement data values. Similarly, in one or moreembodiments, the pump control module 702 may also implement or otherwiseexecute a data prediction application 712 that calculates or otherwisedetermines one or more predicted values for the characteristicquantified by the sensing arrangement 504, 600 based on the sequence ofthe most recent measurement data values provided by the data managementapplication 610. Thus, a predicted value for a sensed characteristic ata time in the future may be influenced by or otherwise based at least inpart on the modified data sequence provided by data managementapplication 710, as described in greater detail below.

Still referring to FIG. 7, depending on the embodiment, the controlmodule 702 may be implemented or realized with a general purposeprocessor, a microprocessor, a controller, a microcontroller, a statemachine, a content addressable memory, an application specificintegrated circuit, a field programmable gate array, any suitableprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof, designed to perform thefunctions described herein. In this regard, the steps of a method oralgorithm described in connection with the embodiments disclosed hereinmay be embodied directly in hardware, in firmware, in a software moduleexecuted by the control module 702, or in any practical combinationthereof. In exemplary embodiments, the pump control module 702 includesor otherwise accesses the data storage element or memory 708, which maybe realized using any sort of non-transitory computer-readable mediumcapable of storing programming instructions for execution by the pumpcontrol module 702. The computer-executable programming instructions,when read and executed by the control module 702, cause the controlmodule 702 to implement or otherwise generate one or more of theapplications 710, 712, 714 and perform the tasks, operations, functions,and processes described in greater detail below.

It should be understood that FIG. 7 is a simplified representation of apump control system 700 for purposes of explanation and is not intendedto limit the subject matter described herein in any way. For example, insome embodiments where the sensing arrangement 504, 600 implements thefeatures and/or functionality of the data management application 710and/or the data prediction application 712, such applications 710, 712may be absent from the pump control system 700. Furthermore, in someembodiments, the features and/or functionality of the motor controlmodule 512 may be implemented by or otherwise integrated into the pumpcontrol system 700 and/or the pump control module 702, for example, bythe command generation application 714 converting the dosage commandinto a corresponding motor command, in which case, the separate motorcontrol module 512 may be absent from an embodiment of the infusiondevice 502.

FIG. 8 depicts an exemplary control process 800 suitable forimplementation by a control system in a fluid infusion device, such asthe control system 500 in the infusion device 502, to determine commandsfor operating a motor to deliver fluid to a user in a manner that isinfluenced by one or more predicted measurement values for a conditionof the user at some point in the future. The various tasks performed inconnection with the control process 800 may be performed by hardware,firmware, software executed by processing circuitry, or any combinationthereof. For illustrative purposes, the following description refers toelements mentioned above in connection with FIGS. 1-7. In practice,portions of the control process 800 may be performed by differentelements of the control system 500, such as, for example, the infusiondevice 502, the sensing arrangement 504, 600, the pump control system520, 700, the motor control module 512, and/or the motor 507. It shouldbe appreciated that the control process 800 may include any number ofadditional or alternative tasks, the tasks need not be performed in theillustrated order and/or the tasks may be performed concurrently, and/orthe control process 800 may be incorporated into a more comprehensiveprocedure or process having additional functionality not described indetail herein. Moreover, one or more of the tasks shown and described inthe context of FIG. 8 could be omitted from a practical embodiment ofthe control process 800 as long as the intended overall functionalityremains intact.

In exemplary embodiments, the control process 800 initializes orotherwise begins by receiving or otherwise obtaining a new measurementdata value (or sample) for a condition in the body of a user andupdating a measurement data sequence of recent measurement data valuesfor the user to include the new measurement data value (task 802, 804).In this regard, the control module 602 may sample, poll, or otherwiseoperate the sensing element 604 to obtain a new sample of the level of acondition in the body 501 of the user. In exemplary embodiments, thecontrol module 602 obtains the new sample from the sensing element 604on a regular periodic basis. For example, the control module 602 maysample the output of the sensing element 604 every five minutes toobtain a new measurement of the blood glucose level in the body 501 ofthe user. After obtaining a new sample, the control module 602 mayobtain a stored sequence of recent measurement samples from the memory608, add the new sample to the sequence of recent measurement samples,and shift the precedence of the previous measurement samples to followthe new measurement sample in the updated measurement sequence. Forexample, the sequence of recent measurement samples may be realized as afirst-in first-out (FIFO) queue of measurement samples that are orderedsequentially, where the control module 602 updates the sequence ofrecent measurement samples by adding the measurement value for the newsample to the FIFO queue and removing the value of the oldestmeasurement sample from the queue. For purposes of explanation, the newor most measurement data value (or sample) may alternatively be referredto herein as the current measurement data value (or sample). In one ormore embodiments, after updating the measurement data sequence, the datamanagement application 610 stores or otherwise maintains the updatedmeasurement sequence in memory 608, for example, by overwriting thepreviously stored measurement sequence. In some embodiments, the memory608 may maintain the previously stored measurement sequence and thecurrent (or updated) measurement sequence in memory 608 to supportinterpolating unusable measurement values using acceptable measurementvalues from the preceding stored measurement sequence, as described ingreater detail below in the context of FIGS. 9-10.

Still referring to FIG. 8, the illustrated control process 800 continuesby determining whether the new measurement sample is usable, and inresponse to determining that the new measurement sample is unusable, thecontrol process 800 flags or otherwise indicates that the newmeasurement sample is unusable (tasks 806, 808). In this regard, whenimplemented by the sensing arrangement 504, 600, the data managementapplication 610 applies various validation criteria and/or logic to thenew measurement sample to verify that the new measurement sample issufficiently accurate and/or reliable before the new measurement sampleis capable of influencing operation of the infusion device 502. Forexample, the data management application 610 may ensure that the newmeasurement sample is greater than a minimum threshold value, less thana maximum threshold value, or otherwise within a range of acceptablevalid measurement values for the condition in the body 501 of the user.Similarly, the data management application 610 may calculate orotherwise obtain one or more characteristics associated with the newmeasurement sample and ensure an obtained characteristic is greater thana minimum threshold value, less than a maximum threshold value, orotherwise within a range of acceptable values for that characteristic ofthe new measurement sample. For example, the data management application610 may determine or obtain a signal-to-noise ratio associated with thenew measurement sample and compare the signal-to-noise ratio to aminimum acceptable signal-to-noise ratio to ensure that the measurementvalue is not likely to have been corrupted or overly influenced bynoise.

When the data management application 610 determines the new measurementsample is unusable (e.g., because its value is not within the range ofacceptable valid measurement values, its signal-to-noise ratio is toolow, or the like), the data management application 610 may flag orotherwise mark the new measurement sample as being invalid or otherwiseunusable so that the measurement value is not utilized when determiningcommands for operating the motor 507 of the infusion device 502. Forexample, in some embodiments, the data management application 610 mayreplace the measurement value with an error code. In other embodiments,the sequence of recent measurement samples may maintain, in associationwith each respective measurement sample in the sequence, an indicationof whether that respective measurement sample is acceptable or otherwiseusable for subsequently determining dosage commands.

In accordance with one or more embodiments, when the current measurementsample is unusable, the sensing arrangement 504, 600 also transmits orotherwise provides the current measurement value and/or the updatedmeasurement sample sequence to the infusion device 502 and/or the pumpcontrol system 520, 700 with a corresponding indication or notificationthat the current (or most recent) measurement is unacceptable. Forexample, the sensing arrangement 504, 600 may transmit or otherwiseprovide an error code for the current measurement sample or anotherindication that the current measurement sample is unusable or otherwiseunacceptable. In some embodiments, when the infusion device 502 and/orthe pump control system 520, 700 receives an error code for the currentmeasurement sample or another an indication that the current measurementsample is unusable or otherwise unacceptable, the pump control system520, 700 and/or the command generation application 714 may implement amodified control scheme or algorithm for determining dosage commandsindependent of any current and/or predicted measurement values in amanner that is likely to maintain the condition in the body 501 of theuser within an acceptable range. In accordance with one embodiment, whenthe delivery has been suspended and more than a threshold number ofunusable measurement samples have been received by the infusion device502 while delivery is suspended, the pump control system 520, 700 and/orthe command generation application 714 may automatically resumedelivery.

Still referring to FIG. 8, when the new measurement sample is acceptableand usable, the control process 800 continues by determining whether thesequence of recent measurement samples is valid or otherwise acceptablefor use in subsequently determining dosage commands for operating theinfusion device (task 810). In this regard, the data managementapplication 610 analyzes each measurement sample in the recentmeasurement sample sequence to ensure that none of the measurementsamples has been flagged or otherwise identified as being unusable. Whenall of the measurement samples in the recent measurement sample sequenceare usable, the control process 800 determines the measurement sequenceis valid and acceptable and proceeds with determining a predictedmeasurement value for the condition in the body of the user at a time inthe future and determining dosage commands for operating the infusiondevice in a manner that is influenced by the predicted measurement value(tasks 818, 820), in a similar manner as described below.

In exemplary embodiments, when the control process 800 determines thatthe sequence of recent measurement samples is invalid or otherwiseunacceptable, the control process 800 continues by determining whetherthe recent measurement sample sequence can be interpolated to substitutemodified measurement values for the measurement samples that have beenflagged or otherwise identified as being unusable (task 812). In thisregard, the data management application 610 determines whether thedifference between two sequential usable values is less than or equal toa threshold number of measurement samples. The threshold number ofmeasurement samples corresponds to a threshold amount of time that isshort enough in duration that interpolating the recent measurementsample sequence to replace the unusable measurement samples between twosequential acceptable values allows any predicted measurement valuescalculated based thereon to achieve a desired level of accuracy and/orreliability. For example, if it is determined that gaps betweensequential usable values that are less than or equal to 20 minutes canbe interpolated and still result in predicted measurement values havinga desired level of accuracy and/or reliability, then the thresholdnumber of measurement samples may be chosen to be the number ofmeasurement samples that would be expected to be obtained within a 20minute timeframe. Continuing the example described above, if the newmeasurement samples are obtained every 5 minutes, a threshold number ofmeasurement samples between sequential usable measurement values equalto 3 measurement samples will allow gaps of up to 20 minutes betweenusable measurement values to be interpolated. Thus, the data managementapplication 610 may interpolate between any two usable measurementsamples that are separated by three or fewer unusable measurementsamples to obtain a modified (or adjusted) recent measurement samplesequence that does not include any invalid and/or unusable measurementvalues.

If the unusable measurement sample(s) in the recent measurement samplesequence can be interpolated, the control process 800 continues byperforming interpolation using preceding and succeeding usablemeasurement samples in the measurement sequence to obtain one or moreinterpolated measurement values corresponding to one or more unusablemeasurement samples in the recent measurement sample sequence (task814). The recent measurement sample sequence is then modified orotherwise adjusted by substituting the interpolated measurement valuesfor the corresponding unusable measurement values, resulting in amodified (or adjusted) recent measurement sample sequence that does notinclude unusable measurement values for samples in the sequence thathave been identified as unusable. For example, the data managementapplication 610 may perform interpolation using any number of acceptablemeasurement samples that precede and/or succeed an unusable measurementsample (or consecutive unusable measurement samples) to determineinterpolated measurement values for the unusable measurement sample(s).In accordance with one embodiment, the data management application 610utilizes linear interpolation to obtain an interpolated measurementvalue for an unusable measurement sample(s) between two usablemeasurement samples. However, it should be appreciated that the subjectmatter described herein is not limited to any particular type ofinterpolation utilized to replace unusable measurement samples. In someembodiments, after modifying the measurement data sequence, the datamanagement application 610 may store or otherwise maintain the modifiedmeasurement sequence in memory 608. In other embodiments, the datamanagement application 610 may provide the modified measurement sequenceto the data prediction application 612 while storing or otherwisemaintaining the original unmodified measurement sequence in memory 608.

When the control process 800 determines recent measurement samplesequence cannot be interpolated, the control process 800 continues byreplacing unusable measurement samples in the recent measurement samplesequence with the value of a more recently obtained usable measurementvalue (task 816). In this regard, when the number of consecutiveunusable measurement samples exceeds a threshold number of measurementsamples that are allowed to be interpolated (alternatively referred toherein as the interpolatable threshold), those consecutive unusablemeasurement samples are replaced with the more recent measurement datavalue that succeeds or follows those unusable measurement samples in therecent measurement sample sequence. In other words, the data managementapplication 610 backfills consecutive unusable measurement samples thatexceed the interpolatable threshold with the more recent usablemeasurement data value that immediately follows those consecutiveunusable measurement samples. In some embodiments, any usablemeasurement samples that precede the consecutive unusable measurementsamples in the recent measurement sample sequence are also replaced orotherwise backfilled to eliminate any potential spike, jump or otherdiscontinuity at the transition from those prior usable measurementsamples to the current measurement sample value being backfilled. Forexample, continuing the example described above, if the interpolatablethreshold number of measurement samples is equal to 3 and the number ofconsecutive unusable measurement samples is greater than or equal to 4,the data management application 610 may replace the consecutive unusablemeasurement samples and any older measurement samples in the recentmeasurement sample sequence with the usable measurement value thatimmediately follows the consecutive unusable measurement samples in thesequence.

It should be noted that in some embodiments of the control process 800,both interpolation and replacement may be performed on a measurementdata sequence to obtain a modified measurement data sequence. Forexample, as described in greater detail below in the context of FIGS.9-10, in situations where there are multiple sets of consecutiveunusable measurement samples in the sequence, any set of consecutiveunusable measurement samples that has fewer than the interpolatablethreshold number may be interpolated while any set of consecutiveunusable measurement samples that has greater than the interpolatablethreshold number may be replaced with the immediately following usablemeasurement value.

Additionally, it should also be noted that in some embodiments of thecontrol process 800, when the measurement sequence is incomplete orotherwise does not contain the steady state number of measurementsamples, the control process 800 may determine that the measurementsequence is not valid and acceptable (e.g., because it does not containthe desired amount of usable measurement values), in which case thecontrol process 800 may proceed by backfilling the measurement sequenceusing the oldest usable measurement value in the measurement sequence.For example, the measurement sequence in memory 608 may initially bepopulated with an error code, a null value, or the like, therebyindicating the samples in the initial measurement sequence are notusable. If the measurement sequence contains 9 samples at steady stateand the current measurement sequence contains only 2 usable samples, thecontrol process 800 may backfill the measurement sequence with the leastrecent of the usable samples to obtain a complete modified measurementdata sequence with the steady state number of measurement sample values.In this regard, upon initialization of the control system 500, predictedvalues for the condition in the body 501 of the user may still becalculated. Furthermore, in yet other embodiments, a complete modifiedmeasurement data sequence may be obtained by extrapolating the usablemeasurement data values backwards to fill the measurement data sequence.

Still referring to FIG. 8, after obtaining a modified recent measurementsample sequence, the control process 800 continues by determining apredicted measurement value for the condition in the body of the user ata time in the future (task 818). In exemplary embodiments, the dataprediction application 612 calculates the predicted measurement valuebased at least in part on the current measurement data value and aweighted sum determined using the measurement data values in the recentmeasurement sample sequence received from the data managementapplication 610 and/or memory 608. Thus, when one or more previouslyunusable measurement samples have been modified, either by interpolationor replacement with a more recent value, the predicted measurement valueis calculated or otherwise determined based at least in part on thosemodified measurement data values in addition to the originallyacceptable measurement values maintained in the modified measurementsequence.

In one or more exemplary embodiments, a predicted blood glucose level inthe body 501 of the user at a time in the future is calculated using theequation ŷ=y_(t)+hb_(t), where ŷ is the predicted blood glucose level,y_(t) is equal to the current (or most recent) blood glucose measurementvalue, h is the prediction horizon in terms of number of measurementsamples in the future from the current time, and b_(t) is the estimateof the trend in the measurements that is determined as a weighted sum ofthe measurement values in the recent measurement sequence. In exemplaryembodiments, b_(t) is governed by the equation

${b_{t} = {\sum\limits_{k = 1}^{n}{{\beta\left( {1 - \beta} \right)}^{({k - 1})}b_{t - k}}}},$where β is a tuning parameter, n is equal to the number of older bloodglucose measurement values in the measurement sequence that precede thecurrent measurement value. The b_(t-k) term is calculated as thedifference between the k^(th) blood glucose measurement value precedingthe current measurement value in the measurement sequence and the bloodglucose measurement value that immediately precedes the k^(th) bloodglucose measurement value in the measurement sequence (e.g.,b_(t-k)=y_(t-k)−y_(t-k-1)). In this regard, t corresponds to the current(or most recent) measurement sampling time (e.g., y_(t) is the first ormost recent measurement sample in the sequence), t−1 corresponds to thepreceding (or next most recent) measurement sampling time (e.g., y_(t-1)is the second most recent measurement sample in the sequence), and soon, such that y_(t-n) corresponds to the oldest (or least recent)measurement sample in the sequence. It should be noted that the estimateof the trend is calculated in a deterministic manner rather than arecursive manner using a truncated Taylor series expansion of theequation b_(t)=β(y_(t)−y_(t-1))+(1−β)b_(t-1), which, in turn, allows theestimate of the trend to be calculated using a modified data sequence inthe event of unusable measurement samples rather than having toreinitialize the calculation. In one embodiment, the anticipated (orexpected) blood glucose level in the body 501 of the user 30 minutesinto the future. Thus, continuing the above example, if the measurementsamples are obtained every 5 minutes, the predicted blood glucose level30 minutes into the future CO is calculated by setting h=6, whichcorresponds to the number of measurement samples that would be obtainedover a 30 minute duration of time.

After determining a predicted measurement value, the control process 800continues by determining commands for operating the infusion device in amanner that is influenced by the predicted measurement value (task 820).For example, the sensing arrangement 504, 600 may transmit or otherwiseprovide the current blood glucose measurement value (y_(t)) and thepredicted blood glucose measurement value (ŷ) in the body 501 of theuser 30 minutes into the future to the pump control system 520, 700.Thereafter, the pump control system 520, 700 and/or command generationapplication 714 determines a dosage command based on the current bloodglucose measurement value and one or more target blood glucosemeasurement value in a manner that is influenced by or otherwiseaccounts for the predicted blood glucose measurement value. For example,the pump control system 520, 700 and/or command generation application714 may determine an initial dosage command based on a differencebetween the current blood glucose measurement value and a target bloodglucose measurement value, and then utilize the predicted blood glucosemeasurement value as a modification factor that increases and/ordecreases that dosage command, which is then provided to the motorcontrol module 512 for generating appropriate motor commands. In someembodiments, the pump control system 520, 700 and/or command generationapplication 714 may set the dosage command to zero when the predictedblood glucose value is less than a lower threshold blood glucose level.As described above in the context of FIG. 5, in response to receiving adosage command, the motor control module 512 may convert the dosagecommand to a corresponding motor command (e.g., a number of steps ofrotor rotation) that will displace the plunger 517 by an amountcorresponding to the desired dosage and then operate the motor 507 toachieve the desired displacement of the plunger 517. In this manner,delivery of the desired amount of fluid from the infusion device 502 tothe body 501 of the user is achieved.

Still referring to FIG. 8, while the foregoing discussion of the controlprocess 800 was described in the context of the sensing arrangement 504,600 detecting or otherwise identifying acceptable and/or unusablemeasurement samples and/or measurement sequences, modifying measurementsequences, and determining predicted measurement values, in alternativeembodiments, one or more of those aspects may be performed by theinfusion device 502 and/or the pump control system 520, 700. Forexample, in one alternative embodiment, the sensing arrangement 504, 600may merely obtain a new measurement value and transmit the newmeasurement value to the pump control system 520, 700, whereby the datamanagement application 710 on the pump control module 702 manages orotherwise maintains the sequence of recent measurement values anddetermines whether the new measurement value is acceptable. In suchembodiments, the pump control system 520, 700 may also account formeasurement values that may have been dropped or otherwise lost intransmission from the sensing arrangement 504, 600 that were notreceived by the communications interface 704. For example, if thesensing arrangement 504, 600 obtains and transmits a new measurementvalue every 5 minutes, the data management application 710 mayautomatically identify an absent measurement sample and update themeasurement sequence to reflect a new unusable measurement sample inresponse to a failure to receive a new measurement value 5 minutes (plusor minus a particular time window or margin for error) after the mostrecently obtained measurement sample. In a similar manner as describedabove, the data management application 710 on the pump control module702 may also detect or otherwise identify an unacceptable and/or invaliddata sequence and modify the measurement sequence using one or moreacceptable measurement values within the measurement sequence (e.g.,tasks 810, 812, 814, 816). Thereafter, the data prediction application712 on the pump control module 702 determines a predicted measurementvalue that is provided to the command generation application 714 forgenerating operating commands for the infusion device 502 (e.g., tasks818, 820), as described above.

In one or more embodiments, the sensing arrangement 504, 600 obtains newmeasurement values, updates the measurement sequences, and transmits themeasurement sequences with a corresponding indication of any unusablemeasurement values in a measurement sequence (e.g., tasks 802, 804, 806,808). In such embodiments, the data management application 710 on thepump control module 702 receives a measurement sequence from the sensingarrangement 504, 600 and determines whether the measurement sequenceneeds to be modified for subsequent usage (e.g., task 810). In thisregard, the data management application 710 may modify unusablemeasurement values indicated by the sensing arrangement 504, 600 whilealso accounting for any measurement samples that may have been droppedor otherwise lost in transmission from the sensing arrangement 504, 600.For example, the data management application 710 may also identifyabsent or missing measurement samples within a measurement sequencereceived from the sensing arrangement 504, 600 that were likely dropped,lost, or otherwise corrupted during transmission.

FIG. 9 is depicts a table 900 including exemplary measurement sequences,and FIG. 10 depicts a table 1000 corresponding to the measurementsequences in the table 900 of FIG. 9 after invalid and/or unacceptablemeasurement sequences have been modified and a corresponding predictedvalue based thereon has been calculated using a in conjunction with thecontrol process 800 described above. In FIG. 9, unusable measurementsamples are identified by setting the corresponding measurement value toa null value. As described above, the unusable measurement samples couldbe measurement samples that did not result in a valid measurement value(e.g., an original measurement value outside the range of valid valuesfor the sensing element 604), measurement samples having a lowsignal-to-noise ratio that are susceptible to being corrupted by noise,absent measurement samples that were lost or otherwise failed to bereceived by the infusion device 502, or the like. The first row of thetables 900, 1000 depicts a valid measurement sequence where all of theindividual measurement samples are originally valid and acceptable. Inthe illustrated embodiment, the predicted values depicted in the table1000 are calculated for the time 6 measurement samples into the future(e.g., h=6) with a tuning parameter of 0.3 (e.g., β=0.3).

The second row in the table 900 depicts a measurement sequence where adifference between two sequential usable measurement samples (e.g.,y_(t) and y_(t-4)) is equal to interpolatable number of measurementsamples (e.g., 3 measurement samples corresponding to an allowable gapof 20 minutes between y_(t) and y_(t-4)). The second row in table 1000depicts the modified measurement sequence obtained by performing linearinterpolation between the usable measurement values for y_(t) andy_(t-4) to replace the measurement samples between y_(t) and y_(t-4)with interpolated measurement values and the corresponding predictedmeasurement value calculated using those interpolated measurementvalues.

The third row in the table 900 depicts a measurement sequence where thedifference between usable measurement samples y_(t-8) and y_(t-6) andthe difference between usable measurement samples y_(t-4) and y_(t-1)are both less than or equal to the interpolatable number of measurementsamples. The third row in table 1000 depicts the modified measurementsequence obtained by performing linear interpolation between the usablemeasurement values for y_(t-8) and y_(t-6) to obtain an interpolatedvalue for y_(t-7) and performing linear interpolation between the usablemeasurement values for y_(t-4) and y_(t-1) to obtain interpolated valuesfor y_(t-3) and y_(t-2).

The fourth row in the tables 900, 1000 depicts a modified measurementsequence where a usable measurement sample (e.g., y_(t-9)) from apreviously stored measurement sequence in memory 608, 706 is used tointerpolate and replace the oldest measurement sample(s) in a currentmeasurement sequence when the next preceding measurement value was anacceptable measurement value (e.g., y_(t-9)=1).

The fifth row in the table 900 depicts a measurement sequence where thedifference between two sequential usable measurement samples y_(t-1) andy_(t-6) is greater than the interpolatable number of measurementsamples. The fifth row in table 1000 depicts the modified measurementsequence obtained by backfilling or otherwise replacing measurementsamples older than y_(t-1) with the measurement value for y_(t-1). Inthis regard, originally acceptable measurement values for y_(t-6),y_(t-7), and y_(t-8) may be overwritten with the value of y_(t-1). Inthis manner, backfilling for y_(t-6), y_(t-7), and y_(t-8) eliminatesthe spike or jump that could otherwise occur when transitioning from theoriginal value of y_(t-6) (e.g., 2) to the backfilled value for y_(t-5)(e.g., 4.5) and effectively resets the prediction algorithm with thevalue of y_(t-1).

The sixth row in the tables 900, 1000 depicts a modified measurementsequence where the oldest measurement samples are unusable and replacedwith the value of the usable measurement sample that succeeds theunusable measurement samples in the sequence.

The seventh row in the table 900 depicts a measurement sequence wherethe oldest two measurement samples in the sequence are unusable andcannot be interpolated because the preceding measurement sample (e.g.,y_(t-9)) is unavailable or unusable. At the same time, the differencebetween usable samples y_(t-3) and y_(t-6) is less than theinterpolatable number of measurement samples. In this regard, theseventh row in table 1000 depicts the modified measurement sequenceobtained by backfilling or otherwise replacing measurement samplesy_(t-7) and y_(t-8) with the usable measurement value for y_(t-6), whilealso performing linear interpolation between the usable measurementvalues for y_(t-3) and y_(t-6) to obtain interpolated values for y_(t-4)and y_(t-5).

As described above, by virtue of calculating the predicted measurementvalue in a deterministic manner rather than a recursive manner, anymeasurement values that are invalid, unacceptable, or otherwise missingfrom a measurement sequence may be interpolated or replaced usingacceptable measurement value(s) to obtain a modified measurementsequence, which may then be utilized to calculate a predictedmeasurement value without compromising the accuracy and/or reliabilityof the prediction. In this regard, a predicted measurement value remainsavailable to the pump control system 520, 700 for influencing operationof the infusion device 502, rather than having to disable the predictivecontrol and wait until a complete and valid measurement sequence isavailable before resuming the predictive control.

For the sake of brevity, conventional techniques related to glucosesensing and/or monitoring, sensor calibration and/or compensation, andother functional aspects of the subject matter may not be described indetail herein. In addition, certain terminology may also be used in theherein for the purpose of reference only, and thus is not intended to belimiting. For example, terms such as “first”, “second”, and other suchnumerical terms referring to structures do not imply a sequence or orderunless clearly indicated by the context. The foregoing description mayalso refer to elements or nodes or features being “connected” or“coupled” together. As used herein, unless expressly stated otherwise,“coupled” means that one element/node/feature is directly or indirectlyjoined to (or directly or indirectly communicates with) anotherelement/node/feature, and not necessarily mechanically.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. For example, the subject matter described herein isnot limited to the infusion devices and related systems describedherein. Moreover, the foregoing detailed description will provide thoseskilled in the art with a convenient road map for implementing thedescribed embodiment or embodiments. It should be understood thatvarious changes can be made in the function and arrangement of elementswithout departing from the scope defined by the claims, which includesknown equivalents and foreseeable equivalents at the time of filing thispatent application. Accordingly, details of the exemplary embodiments orother limitations described above should not be read into the claimsabsent a clear intention to the contrary.

What is claimed is:
 1. A method of operating a device, the methodcomprising: obtaining a sequence of measurements indicative of acondition of a user; modifying one or more unusable measurements in thesequence using one or more other measurements in the sequence to obtaina modified sequence of measurements, wherein modifying the one or moreunusable measurements comprises: determining a gap between a precedingusable measurement for the one or more unusable measurements and asucceeding usable measurement for the one or more unusable measurements;replacing the one or more unusable measurements by interpolating the oneor more unusable measurements using the preceding usable measurement inthe sequence and the succeeding usable measurement when the gap is lessthan a threshold; and backfilling the one or more unusable measurementswith the succeeding usable measurement when the gap is greater than thethreshold; determining a predicted value for the condition based atleast in part on the modified sequence of measurements; and operatingthe device in a manner that is influenced by the predicted value.
 2. Themethod of claim 1, the device comprising an infusion device capable ofdelivering fluid to the user, the fluid influencing the condition of theuser, wherein operating the device comprises operating the infusiondevice in a manner that is influenced by the predicted value.
 3. Themethod of claim 2, the infusion device being capable of deliveringinsulin to the user, wherein: obtaining the sequence of measurementscomprises obtaining a sequence of glucose measurements; modifying one ormore unusable measurements in the sequence comprises modifying one ormore unusable glucose measurements in the sequence using one or moreusable glucose measurements in the sequence to obtain a modifiedsequence of glucose measurements; determining the predicted valuecomprises determining a predicted glucose for the user at a time in thefuture based at least in part on the modified sequence of glucosemeasurements; and operating the device comprises operating the infusiondevice in a manner that is influenced by the predicted glucose in thefuture.
 4. The method of claim 3, wherein operating the infusion devicein a manner that is influenced by the predicted glucose comprises:determining a dosage command based at least in part on a current glucosemeasurement in the sequence; and adjusting the dosage command based atleast in part on the predicted glucose in the future.
 5. The method ofclaim 1, wherein determining the predicted value comprises determiningthe predicted value based at least in part on a weighted sum of valuesof the modified sequence of measurements.
 6. The method of claim 1, themodified sequence including a current measurement for the condition,wherein determining the predicted value comprises determining thepredicted value as a sum of the current measurement and a weighted sumof differences between consecutive measurements in the modified sequencethat precede the current measurement.
 7. The method of claim 6, furthercomprising: identifying an unusable measurement in the sequence, whereinmodifying the one or more unusable measurements comprises: replacing theunusable measurement with a value of the succeeding usable measurementin the sequence when the gap is greater than the threshold; and when thegap is less than the threshold: interpolating unusable measurement usingthe preceding usable measurement in the sequence and the succeedingusable measurement in the sequence to obtain an interpolated value; andreplacing the unusable measurement with the interpolated value.
 8. Amethod of operating a device, the method comprising: obtaining asequence of measurements indicative of a condition of a user; modifyingone or more unusable measurements in the sequence using one or moreother measurements in the sequence to obtain a modified sequence ofmeasurements; determining a predicted value for the condition based atleast in part on the modified sequence of measurements, whereindetermining the predicted value for the condition based at least in parton the modified sequence of measurements comprises: determining anestimate of a trend in the sequence of measurements based at least inpart on differences between consecutive measurements of the modifiedsequence of measurements; and determining the predicted value for thecondition of the user at a time in the future based at least in part ona current value for the condition and the estimate of the trend; andoperating the device in a manner that is influenced by the predictedvalue.
 9. The method of claim 8, wherein modifying one or more unusablemeasurements in the sequence using one or more other measurements in thesequence comprises backfilling the one or more unusable measurementswith a succeeding usable measurement.
 10. The method of claim 8,wherein: determining the estimate of the trend comprises calculating theestimate of the trend using a truncated Taylor series expansion of theequation b_(t)=β(y_(t)−y_(t-1))+(1−β)b_(t-1); determining the predictedvalue comprises determining the predicted value using the equationŷ=y_(t)+hb_(t); ŷ is the predicted value; y_(t) is equal to a mostrecent measurement in the sequence of measurements; h is a predictionhorizon number of measurement samples in the future; b_(t) is theestimate of the trend; and β is a tuning parameter.
 11. A method ofoperating an infusion device capable of delivering fluid to a user, thefluid influencing a physiological condition of the user, the methodcomprising: obtaining a sequence of measurements indicative of thephysiological condition of the user; modifying one or more unusablemeasurements in the sequence using one or more other measurements in thesequence to obtain a modified sequence of measurements; determining anestimate of a trend in the sequence of measurements based at least inpart on differences between consecutive measurements of the modifiedsequence of measurements; determining a predicted value for thephysiological condition of the user at a time in the future based atleast in part on a current value for the physiological condition and theestimate of the trend; determining a dosage command for operating amotor of the infusion device based at least in part on the current valuefor the physiological condition and the predicted value for thephysiological condition; and operating the motor of the infusion deviceto deliver the fluid in a manner that is influenced by the predictedvalue.
 12. The method of claim 11, wherein modifying one or moreunusable measurements in the sequence using one or more othermeasurements in the sequence comprises backfilling the one or moreunusable measurements with a succeeding usable measurement.
 13. Themethod of claim 11, further comprising determining a gap between apreceding usable measurement for the one or more unusable measurementsand a succeeding usable measurement for the one or more unusablemeasurements, wherein modifying the one or more unusable measurementscomprises: replacing the one or more unusable measurements byinterpolating the one or more unusable measurements using the precedingusable measurement in the sequence and the succeeding usable measurementwhen the gap is less than a threshold; and backfilling the one or moreunusable measurements with the succeeding usable measurement when thegap is greater than the threshold.
 14. The method of claim 11, whereindetermining the dosage command comprises: determining the dosage commandbased on a difference between the current value and a target value; andadjusting the dosage command based on the predicted value.
 15. Themethod of claim 14, wherein adjusting the dosage command comprisesdecreasing the dosage command when the predicted value is below asuspend delivery threshold value.
 16. The method of claim 14, whereinadjusting the dosage command comprises increasing the dosage commandwhen the predicted value is above a resume delivery threshold value. 17.The method of claim 14, wherein: the fluid comprises insulin; thesequence of measurements comprises a sequence of glucose measurements;the modified sequence comprises a modified sequence of glucosemeasurements; the predicted value comprises a predicted glucose for theuser at the time in the future; determining the dosage command comprisesdetermining the dosage command based on a difference between a currentglucose measurement value and a target glucose measurement value; andadjusting the dosage command based on the predicted value comprises:decreasing the dosage command when the predicted glucose is below asuspend delivery threshold value; and increasing the dosage command whenthe predicted glucose is above a resume delivery threshold value.